Regional anesthesia in resource-limited and disaster environments: a daring discourse.

Regional anesthesia (RA) is commonly used in perioperative settings of developed and well-resourced environments. RA has significant potential benefits when used in resource-limited environments, including disaster, mass casualty, and wartime environments. RA offers benefits over general anesthesia and opioid-based analgesia, including decreased risk of complications, decreased reliance on mechanical ventilation, improved cost efficiency, and others. The decreasing cost of ultrasound matched with its smaller size and portability increases the availability of ultrasound in these environments, making ultrasound-guided RA more feasible. This daring discourse discusses some historical examples of RA in ultralow resource environments, both man-made disasters and natural disasters. Future investigations should increase the usefulness and availability of RA in resource-limited environments.

Distributed Maritime Operations and the Medical Challenge: How a Medical Common Operating Picture Can Help Bridge the Gap.

This work explores the challenges of delivering medical care in the geographically dispersed and resource-constrained environment of Distributed Maritime Operations (DMO) and Expeditionary Advanced Base Operations (EABO). Traditional medical planning approaches may struggle to adapt to the vast operational space, extended evacuation times, and limited medical force present in these scenarios. The concept of a Medical Common Operating Picture (COP) emerges as a potential solution. By providing a shared view of the medical situation across the theater, encompassing logistics, personnel, and patient data, a medical COP has the potential to facilitate medical command and control (MED C2) in DMO/EABO. The implementation of a medical COP has the potential to optimize resource allocation, enhance situational awareness, streamline medical evacuation, and reduce healthcare provider moral injury in large-scale combat operations. A medical COP will allow medical planners to make informed decisions on triage, resupply, and evacuation, ensuring the best use of limited medical resources. This is done by leveraging a comprehensive understanding of the medical landscape, enabling informed clinical and operational decision-making by humanitarian and combat personnel respectively. A fully realized medical COP system will enable a dynamic theater evacuation policy, balancing the conflicting needs of patient care at higher echelons with the operational expediency of returning servicemembers to their operational units, thereby maximizing evacuation effectiveness. It will further enable medical personnel to perform dynamic casualty triage based on operational realities, mitigating potential ethical dilemmas. Implementing such a medical COP system will require overcoming communication limitations to facilitate data exchange and potentially integrating clinical decision support tools for real-time data analysis and recommendations. It will also require the rapid adoption of modernized operational medicine documentation solutions by medical assets within the operational forces. Ultimately, this work suggests that a medical COP has the potential to bridge the gap between traditional medical planning and the unique demands of DMO/EABO, ultimately optimizing casualty care, maximizing resource efficiency, and preserving the fighting force.

Tropical Diseases in Okinawa: Overview and Emerging Infectious Diseases.

Okinawa prefecture is at risk for emerging infectious diseases due to its subtropical climate and its location within the Indo-Pacific region. Understanding the existing vectors and infectious agents contextualizes current threats, guides treatment, and informs prevention, and may be of unique concern in the setting of complex emergencies.

Marine Envenomation in Okinawa: Overview and Treatment Concept.

Okinawa prefecture is a popular tourist destination due to its beaches and reefs. The reefs host a large variety of animals, including a number of venomous species. Because of the popularity of the reefs and marine activities, people are frequently in close contact with dangerous venomous species and, thus, are exposed to potential envenomation. Commonly encountered venomous animals throughout Okinawa include the invertebrate cone snail, sea urchin, crown-of-thorns starfish, blue-ringed octopus, box jellyfish, and fire coral. The vertebrates include the stonefish, lionfish, sea snake, and moray eel. Treatment for marine envenomation can involve first aid, hot water immersion, antivenom, supportive care, regional anesthesia, and pharmaceutical administration. Information on venomous animals, their toxins, and treatment should be well understood by prehospital care providers and physicians practicing in the prefecture.

Surgical Casualty Care in Contested Distributed Maritime Operations: Lessons Learned From the Falklands War.

The Falklands Campaign was fought a significant distance from the home base of the British Fleet. The planning and delivery of medical care during this campaign can provide significant lessons for strategic medical planning in other far spread geographic locations, including the Indo-Pacific region. Consideration of doctrine, including Role 1-4 facilities and the golden hour, may need to be reconsidered in light of changing scenarios. New concepts such as the "90-in-90" and "3-in-3" are also discussed as a framework for future planning in the U.S. Indo-Pacific Command area of responsibility.

Whole blood transfusion among allied partnerships: unified and interoperable blood banking for optimised care.

Whole blood transfusion is being increasingly used for trauma resuscitation, particularly in military settings. Low-titre group O whole blood simplifies the logistical challenges and maximises the benefits of blood transfusion when compared with component therapy in austere battlefield conditions. Screening protocols and blood testing requirements for prescreened donors in walking blood banks (WBBs), which are used for emergency transfusions, are established by both the USA and most partner nations, though they are not necessarily uniform across these combined forces. Interoperability and standardisation of blood bank resources and protocols across allied forces in multinational military operations, including uniformity in screening processes, collection methods and storage is essential to the provision of safe and effective blood product transfusions in this austere setting. Predeployment screening, multinational training exercises and universal WBB sets with instructions in multiple languages can help enhance the interoperability of combined multinational operations and create a more efficient WBB system. Standardisation of blood collection, nomenclature, equipment and screening practices will allow for the most optimal utilisation of whole blood resources across a multinational battlefield.

Military concerns for chronic pain stimulator devices.

Spinal cord stimulators (SCS) and peripheral nerve stimulators (PNS) are increasingly used in the treatment of chronic pain, allowing more patients to resume working and return to activities. Military service members face environmental and occupational hazards that expose them to mechanical and electromagnetic forces, both clinical and industrial, that could potentially alter their function. While there are reports of individual hazards, the risk appears to be nominal based on the large number of devices in use and the limited reported complications with these devices. Since a variety of hazards encountered by military patients have the potential to alter SCS and PNS devices, a brief discussion of each patient's specific exposures and related hazards should occur prior to placement. Overall, these devices have demonstrated safety in hazardous areas and few military patients have contraindications for placement based on these factors alone.

The Association Between Borderline Dysnatremia and Perioperative Morbidity and Mortality: Retrospective Cohort Study of the American College of Surgeons National Surgical Quality Improvement Program Database.

BACKGROUND: Hyponatremia and hypernatremia, as conventionally defined (<135 mEq/L and >145 mEq/L, respectively), are associated with increased perioperative morbidity and mortality. However, the effects of subtle deviations in serum sodium concentration within the normal range are not well-characterized. OBJECTIVE: The purpose of this analysis is to determine the association between borderline hyponatremia (135-137 mEq/L) and hypernatremia (143-145 mEq/L) on perioperative morbidity and mortality. METHODS: A retrospective cohort study was performed using data from the American College of Surgeons National Surgical Quality Improvement Program database. This database is a repository of surgical outcome data collected from over 600 hospitals across the United States. The National Surgical Quality Improvement Program database was queried to extract all patients undergoing elective, noncardiac surgery from 2015 to 2019. The primary predictor variable was preoperative serum sodium concentration, measured less than 5 days before the index surgery. The 2 primary outcomes were the odds of morbidity and mortality occurring within 30 days of surgery. The risk of both outcomes in relation to preoperative serum sodium concentration was modeled using weighted generalized additive models to minimize the effect of selection bias while controlling for covariates. RESULTS: In the overall cohort, 1,003,956 of 4,551,726 available patients had a serum sodium concentration drawn within 5 days of their index surgery. The odds of morbidity and mortality across sodium levels of 130-150 mEq/L relative to a sodium level of 140 mEq/L followed a nonnormally distributed U-shaped curve. The mean serum sodium concentration in the study population was 139 mEq/L. All continuous covariates were significantly associated with both morbidity and mortality (P<.001). Preoperative serum sodium concentrations of less than 139 mEq/L and those greater than 144 mEq/L were independently associated with increased morbidity probabilities. Serum sodium concentrations of less than 138 mEq/L and those greater than 142 mEq/L were associated with increased mortality probabilities. Hypernatremia was associated with higher odds of both morbidity and mortality than corresponding degrees of hyponatremia. CONCLUSIONS: Among patients undergoing elective, noncardiac surgery, this retrospective analysis found that preoperative serum sodium levels less than 138 mEq/L and those greater than 142 mEq/L are associated with increased morbidity and mortality, even within currently accepted "normal" ranges. The retrospective nature of this investigation limits the ability to make causal determinations for these findings. Given the U-shaped distribution of risk, past investigations that assume a linear relationship between serum sodium concentration and surgical outcomes may need to be revisited. Likewise, these results question the current definition of perioperative eunatremia, which may require future prospective investigations.

Effect of needle type on plane block spread in a cadaveric porcine model.

INTRODUCTION: Plane blocks are an increasingly common type of regional anaesthesia technique in the perioperative period. Increased spread of local anaesthesia during plane blocks is thought to be related to an increased area of pain coverage. This study sought to assess differences in injectate spread comparing Tuohy needles with standard insulated stimulating block needles. METHODS: 10 Yorkshire-Cross porcine cadavers were used in this study. Immediately following euthanasia, the cadavers underwent bilateral ultrasound-guided transversus abdominis plane (TAP) block injection with radiopaque contrast dye, with one side placed with a 20 g Tuohy needle, and the other side with a 20 g insulated stimulating block needle. Injectate spread was assessed using plain film X-ray and area of spread was measured to compare differences. RESULTS: All 10 animals underwent successful ultrasound-guided TAP block placement. In all 10 animals, the area of contrast spread was greater with the Tuohy than stimulating needle. Wilcoxon signed-rank test was used to analyse the difference between the groups. The average difference between the two sides was 33.02% (p=0.002). CONCLUSIONS: This is the first study to demonstrate differences in injectate spread with different needle types. This suggests enhanced spread with Tuohy needle compared with standard block needle, and may encourage its use during plane blocks.

Machine Learning to Predict Discharge Destination After Total Knee Arthroplasty and Total Hip Arthroplasty.

Discharge destination impacts costs and perioperative planning for primary total knee (TKA) or hip arthroplasty (THA). The purpose of this study was to create a tool to predict discharge destination in contemporary patients. Models were developed using more than 400,000 patients from the National Surgical Quality Improvement Program database. Models were compared with a previously published model using area under the receiver operating characteristic curve (AUC) and decision curve analysis (DCA). AUC on patients with TKA was 0.729 (95% confidence interval [CI]: 0.719 to 0.738) and 0.688 (95% CI: 0.678 to 0.697) using the new and previous models, respectively. AUC on patients with THA was 0.768 (95% CI: 0.758 to 0.778) and 0.726 (95% CI: 0.714 to 0.737) using the new and previous models, respectively. DCA showed substantially improved net clinical benefit. The new models were integrated into a web-based application. This tool enhances clinical decision making for predicting discharge destination following primary TKA and THA. (Journal of Surgical Orthopaedic Advances 32(4):252-258, 2023).

Pulse Arrival Time Is Associated With Hemorrhagic Volume in a Porcine Model: A Pilot Study.

BACKGROUND: Hemorrhage is a major cause of preventable death worldwide, and early identification can be lifesaving. Pulse wave contour analysis has previously been used to infer hemodynamic variables in a variety of settings. We hypothesized that pulse arrival time (PAT), a form of pulse wave contour analysis which is assessed via electrocardiography (ECG) and photoplethysmography (PPG), is associated with hemorrhage volume. METHODS: Yorkshire-Cross swine were randomized to hemorrhage (30 mL/kg over 20 minutes) vs. control. Continuous ECG and PPG waveforms were recorded with a novel monitoring device, and algorithms were developed to calculate PAT and PAT variability throughout the respiratory cycle, termed "PAT index" or "PAT_I." Mixed effects models were used to determine associations between blood loss and PAT and between blood loss and PAT_I to account for clustering within subjects and investigate inter-subject variability in these relationships. RESULTS: PAT and PAT_I data were determined for ∼150 distinct intervals from five subjects. PAT and PAT_I were strongly associated with blood loss. Mixed effects modeling with PAT alone was substantially better than PAT_I alone (R2 0.93 vs. 0.57 and Akaike information criterion (AIC) 421.1 vs. 475.5, respectively). Modeling blood loss with PAT and PAT_I together resulted in slightly improved fit compared to PAT alone (R2 0.96, AIC 419.1). Mixed effects models demonstrated significant inter-subject variability in the relationships between blood loss and PAT. CONCLUSIONS: Findings from this pilot study suggest that PAT and PAT_I may be used to detect blood loss. Because of the simple design of a single-lead ECG and PPG, the technology could be packaged into a very small form factor device for use in austere or resource-constrained environments. Significant inter-subject variability in the relationship between blood loss and PAT highlights the importance of individualized hemodynamic monitoring.

Military Pain Medicine: Sustaining the Fighting Force.

Active duty military service members (ADSMs) suffer disproportionately from chronic pain. In the USA, military pain physicians serve an important role in the treatment of pain conditions in addition to the maintenance of the fighting force. Expanding roles for pain physicians, including novel therapies, consulting roles for opioid policy, and usefulness in a deployed setting create enormous value for military pain physicians. Ongoing force structure changes, including proposed reduction in the U.S. Military's healthcare workforce may significantly impact pain care and the health of the fighting forces. Military pain physicians support a variety of different roles in the military healthcare system. Ultimately, maintaining a robust faculty of pain physicians allows for both preservation of the fighting forces and a ready medical force.

Refining the rat sciatic nerve block: a novel ultrasound-guided technique.

Murine translational models are an important tool to understand pain pathophysiology. One procedure used frequently in murine research is the sciatic nerve block. This study sought to demonstrate the use of ultrasound-guided sciatic nerve block in a cadaveric murine model. A total of 40 injections were performed in 20 Sprague-Dawley male 18-month-old rat cadavers. Necropsy was performed to identify staining of the sciatic nerve. Staining with methylene blue occurred in 40 of 40 ultrasound-guided injections. The extremely accurate nature of this block under ultrasound guidance is favorable for future translational studies in rats undergoing sciatic nerve blocks. This method may represent a significant improvement in current methods.

Impact of a Multidisciplinary Long-Term Opioid Therapy Safety Program at a Military Tertiary Academic Medical Center.

OBJECTIVE: In light of the ongoing opioid crisis, Naval Medical Center Portsmouth (NMCP) created the Long-Term Opioid Therapy Safety (LOTS) program to reduce risks and improve long-term opioid therapy outcomes. Our primary outcome was change in compliance with the recommended safety metrics. DESIGN: This is a retrospective cohort study performed at NMCP, a large military academic medical center providing comprehensive medical care to DoD beneficiaries. The NMCP LOTS program provides both patient and provider narcotic education as well as medical record auditing. The NMCP LOTS program promotes adherence to published CDC, the DVA, and DoD guidelines. METHODS: Anonymized data were compiled each fiscal quarter and were analyzed retrospectively. Adult patients prescribed opioids for at least 90 days without a gap of 30 days between prescriptions were included in this study. The investigators recorded and reported provider compliance with LOTS metrics over the same period. RESULTS: Compliance with the recommended safety metrics improved. We noted a decrease in the number of long-term opioid patients, concurrent benzodiazepine prescriptions, and patients prescribed greater than 90 morphine equivalents per day during the observation period. The number of naloxone prescriptions for LOTS patients also increased, reflecting improved guideline adherence. CONCLUSION: Systematic education and feedback to providers are effective in creating a system and culture of opioid reduction, safe opioid prescribing, and system accountability. This article presents a comprehensive approach to modifying prescribing patterns of long-term opioids in a large healthcare system.

Hemodynamic Effects of Cardiovascular Medications in a Normovolemic and Hemorrhaged Yorkshire-cross Swine Model.

The Yorkshire-cross swine model is a valuable translational model commonly used to study cardiovascular physiology and response to insult. Although the effects of vasoactive medications have been well described in healthy swine, the effects of these medications during hemorrhagic shock are less studied. In this study, we sought to expand the utility of the swine model by characterizing the hemodynamic changes that occurred after the administration of commonly available vasoactive medications during euvolemic and hypovolemic states. To this end, we anesthetized and established femoral arterial, central venous, and pulmonary arterial access in 15 juvenile Yorkshire-cross pigs. The pigs then received a series of rapidly metabolized but highly vasoactive medications in a standard dosing sequence. After completion of this sequence, each pig underwent a 30-mL/kg hemorrhage over 10 min, and the standard dosing sequence was repeated. We then used standard sta- tistical techniques to compare the effects of these vasoactive medications on a variety of hemodynamic parameters between the euvolemic and hemorrhagic states. All subjects completed the study protocol. The responses in the hemorrhagic state were often attenuated or even opposite of those in the euvolemic state. For example, phenylephrine decreased the mean arterial blood pressure during the euvolemic state but increased it in the hemorrhagic state. These results clarify previously poorly defined responses to commonly used vasoactive agents during the hemorrhagic state in swine. Our findings also demonstrate the need to consider the complex and dynamic physiologic state of hemorrhage when anticipating the effects of vasoactive drugs and planning study protocols.

Regional Anesthesia for Symptomatic Treatment of Stingray Envenomation.

Stingray envenomation is common in coastal regions around the world and may result in intense pain that can be challenging to manage. Described therapies involve hot water immersion and potentially other options such as opioid and nonopioid analgesics, removal of the foreign body, wound debridement, antibiotics for secondary infection, and tetanus toxoid. However, for some patients, this may not be enough. Peripheral nerve blockade is a frequently used perioperative analgesic technique, but it has rarely been described in the management of stingray envenomation. Here, we report a case of stingray envenomation in an otherwise healthy 36-y-old male with pain refractory to traditional therapies. After admission for pain control, the patient received an ultrasound-guided sciatic popliteal nerve block. Upon completion of the peripheral nerve block, the patient reported rapid and complete resolution of the intense pain, which did not return thereafter.

Machine Learning to Predict Fascial Dehiscence after Exploratory Laparotomy Surgery.

BACKGROUND: Fascial dehiscence following exploratory laparotomy is associated with significant morbidity and increased mortality. Previously published risk prediction models for fascial dehiscence are dated and limit a surgeon's ability to perform reliable risk assessment intraoperatively. We sought to determine if machine learning can predict fascial dehiscence after exploratory laparotomy. MATERIALS AND METHODS: A retrospective cohort study was conducted of 93,024 patients undergoing exploratory laparotomy from the 2011-2018 ACS NSQIP data files. Data were divided into training (2011-2016, n = 69,969) and temporal validation (2017-2018, n = 23,055) cohorts. A clinical decision support tool was developed using the model generated via machine learning techniques. RESULTS: 1,332 (1.9%) patients in the training cohort and 390 (1.7%) patients in the temporal validation cohort developed fascial dehiscence. The area under the receiver operating characteristic curve was 0.69 (95% CI 0.66 to 0.72) in the validation cohort. Model predictions demonstrated excellent probability calibration. Decision curve analysis calculates net clinical benefit within a threshold range of 0.8%-4.5%. Operative time, surgical site and deep space infections, and body mass index were among the most important features for model predictions. Finally, operative time, sodium level, and hematocrit demonstrated non-linear relationships with predicted risk. CONCLUSION: A clinical decision support tool for predicting fascial dehiscence after exploratory laparotomy was created and validated on a contemporary, national patient cohort using machine learning. The tool calculates net clinical benefit and can be used at the point of care. Some identified risk factor relationships were found to be complex and non-linear, highlighting the ability of some machine learning applications to capture nuanced, patient-specific risk profiles.

Ultrasound Versus Fluoroscopy for Stellate Ganglion Block: A Cadaveric Study.

OBJECTIVE: Post-Traumatic Stress Disorder (PTSD) is a common psychiatric disorder. Recent investigations have demonstrated effectiveness of Stellate Ganglion Blocks (SGB) for reducing symptoms associated with PTSD. Both fluoroscopic guided and ultrasound guided SGB have been described and are regularly used in clinical practice. This study sought to evaluate differences in block performance when comparing fluoroscopic versus ultrasound guided SGB. DESIGN: Cadaveric Pilot Study. SETTING: Academic Research Laboratory. SUBJECTS: Ten Soft-Cured Human Cadavers. METHODS: Ten soft-cured human cadavers were used after being at room temperature for 3 hours. Fluoroscopic and ultrasound guided injections were both performed on each cadaver, randomized to left or right sidedness. In total, 7 mL of omnipaque and methylene blue (5:1) was injected in each side. Injectate spread was assessed by measuring vertebral body spread under fluoroscopy. Successful staining of the sympathetic trunk was assessed under cadaveric dissection, with visualization of the sympathetic trunk stained with methylene blue. RESULTS: Ultrasound guided injections resulted in successful staining in 9 of 10 injections, while 6 of 10 for fluoroscopic guidance (P = .3034). The average spread in the ultrasound group was 4.0 compared with 5.2 for the fluoroscopic group (P =.088). In the four fluoroscopic guided injections which failed to stain, the injection occurred posterior to the prevertebral fascia. In the single ultrasound guided block that failed to stain, the injection was in the carotid sheath. CONCLUSIONS: While there appeared to be a trend favoring ultrasound guidance, no statistical significance was achieved. This was likely due to this being a limited pilot study. Numerous limitations exist in cadaveric studies, and future investigations should be completed to further study this comparison. That said, the use of the SGB may provide significant relief for patients suffering with PTSD.